Hillary Clinton's campaign is going on the air in solid-red Texas, a remarkable move by a Democratic presidential nominee as her Republican rival, Donald Trump, struggles across the country.

Clinton is launching a one-week ad buy in the Lone Star State that highlights the Dallas Morning News' recent endorsement of the former U.S. secretary of state, according to a campaign aide. The 30-second commercial will air on TV in Dallas, Houston, Austin and San Antonio, as well as online. Clinton's campaign did not detail the size of the buy.

When the Dallas Morning News editorial board endorsed Clinton earlier this year, it was the board's first endorsement of a Democratic presidential hopeful since before World War II. The Clinton spot notes the historical significance of the endorsement, going on to quote its criticism of Trump's judgment and praise of Clinton's bipartisan credentials.

"At this moment in time, for Texas and for America, Hillary for president," a narrator concludes.

The ad buy comes as polls continue to show the presidential race in Texas closer than usual. A WFAA/SurveyUSA poll released Thursday found Trump leading by only 4 points, much less than Mitt Romney’s 16-point margin in 2012 and John McCain’s 12-point margin in 2008.

"The Dallas Morning News points out Trump's values are out of step with Texas," Garry Mauro, who chairs Clinton's efforts in Texas, said in a statement on the ad buy. "As more and more Texans realize this — and turn to Hillary — the polls will get better and better."

The Texas Republican Party declined to comment.

While the campaign's heightened focus on Texas has excited the state's Democrats and aided down-ballot candidates, it remains to be seen whether its investment in the state reflects a serious play for its 38 electoral college votes. A Democratic presidential nominee has not carried the state since Jimmy Carter in 1976.

On a conference call Monday morning, Texas was not mentioned as Clinton campaign manager Robby Mook detailed so-called “expansion states” where the campaign is making additional substantial investments in the home stretch of the race. The states included Arizona, Indiana and Missouri.

"We will continue to monitor other states across the country to look for opportunities for Democrats to work together,” Mook told reporters.

The Texas ad is nonetheless a rare development in a state that typically receives minimal attention from presidential campaigns during the general election. This cycle the Clinton campaign has opened half a dozen offices in the state and sent vice presidential nominee Tim Kaine and other surrogates for not just fundraisers but also public events.